Priority is claimed on Japanese Patent Application No. 2007-61502 filed Mar. 12, 2007 the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a steering retention state judging device, a driver wakefulness predicting device and a correct course keeping device.
2. Description of Related Art
Technology to predict driver's driving state from steering quantities (steering torque, steering angle, and so on) in a vehicle has been proposed. For example, according to the Japanese Unexamined Patent Application, First Publication No. 2005-119539 technology is disclosed for predicting in advance a slip of a driver's hand during steering operation, by calculating the gripping force of the hands of the driver holding the steering wheel, and by calculating counter-force of the steering wheel, and making the prediction based on the gripping force and the counter-force.
Many examples of traffic accidents have been observed as a result of acknowledgment errors or judgmental errors made by drivers driving in a state of low wakefulness. Thus, development of technology to judge the state of wakefulness of drivers is desired.
However, prior arts to estimate the driving state proposed until now, including the art disclosed in the Japanese Unexamined Patent Application, First Publication No. 2005-119539 generally estimate the driving state passively based on data obtained from steering behavior. According to such prior art, if the driver does not operate the steering wheel, the required data cannot be obtained. The problem here is that on straight roads where the frequency of driver operating the steering wheel is small, considerable time is required to recognize the driving state of the driver.
Thus, a first object of the present invention is to provide a steering retention state judging device that can accurately judge the steering retention state of the driver.
A second object of the present invention is to provide a driver wakefulness predicting device that can estimate the wakefulness of the driver accurately.
Moreover, a third object of the present invention is to provide a correct course keeping device that can accurately maintain the correct course.